How can you trust them?

Today, on my Windows box at work (well, it’s my ONLY Windows box, anyway) there was some updates. As I’m curious, I decided to go with the custom install, just to see what would be upgraded. It was just one simple update, something to allow smaller update packages, as far as I got. But one thing really got me:

“You may have to restart your computer after this install”.

MAY have”?!? What, didn’t they know what the fuck their update would do? What’s next? An update that may fix a serious vulnerability, but they aren’t sure about it?